How to Install a Multi-Spray Shower

Valves

• A typical shower usually functions on a pressure balancing valve. The valve responds to changes in water pressure and temperature and corrects accordingly. This is a very efficient valve for a single showerhead, but it cannot work for multiple water sources. To install a multi-spray shower, start with a thermostatic valve, which responds to temperature alone. Paired with the thermostatic valve are a series of volume control valves; install one volume control for each source of water. The thermostatic valve lets you set the temperature of the water, while the volume controls let you pick and choose which one of the showerheads or sprays you want turned on at one time.

Water Source

• Showerheads and shower sprays all put out water at an assigned amount. Showerheads start putting out water at 2 1/2 gallons per minute, or gpm, and can go as high as 10 gpm for some larger deluge style heads. Body sprays put out a consistent 2 1/2 gpm. A shower with three body sprays and two showerheads may need as much as 27 1/2 gallons of water per minute. If your house is supplied by a well, the typical yield from a well is only 5 gpm, which is not sufficient for a multi-spray shower of any kind. If your house has street water, contact your town to find out the typical gpm, and plan your shower sprays accordingly.

Water Pressure

• Even if you have an adequate supply of water leading to your showerhead, you will still need adequate pressure to supply the various sprays. In order to supply a minimum of three sources of water in your shower, make sure your house's water pressure is a minimum of 50 pounds or pound-force per square inch, which is abbreviated as psi. The more water sources you add, the higher your pressure must be. If necessary, replace your plumbing with 3/4-inch pipes to help increase pressure. Use a 3/4-inch thermostatic valve, regardless of the size of the pipes, and consider adding a pump to help build pressure if the pressure is still too low.

Water Heater

• Most homes have a typical 50-gallon water heater installed. This is more than adequate for most homes, but will not supply an adequate amount of hot water for a multi-spray shower. Remember that a typical multi-spray shower may use as many as 27 gallons of water per minute. If you have a 50-gallon hot water heater, you will get less than two minutes of hot water in this scenario. To correct this, reduce the number of sprays, or the amount of gpm per spray, or install a 100-gallon water heater to help increase the amount of hot water per shower.